Provided are compositions, methods, and systems relating to cementing operations and, in certain examples, to including synthetic hectorite in glass bead suspensions for use in cement compositions.
Cement compositions may be used in a variety of subterranean operations. For example, in subterranean well construction, a pipe string (e.g., casing, liners, expandable tubulars, etc.) may be run into a wellbore and cemented in place. The process of cementing the pipe string in place is commonly referred to as “primary cementing.” In a typical primary cementing method, a cement composition may be pumped into an annulus between the walls of the wellbore and the exterior surface of the pipe string disposed therein. The cement composition may set in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement (i.e., a cement sheath) that may support and position the pipe string in the wellbore and may bond the exterior surface of the pipe string to the subterranean formation. Among other things, the cement sheath surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protecting the pipe string from corrosion. Cement compositions also may be used in remedial cementing methods, for example, to seal cracks or holes in pipe strings or cement sheaths, to seal highly permeable formation zones or fractures, to place a cement plug, and the like.
A broad variety of cement compositions have been used in subterranean cementing operations. In some instances, cement compositions comprising glass beads have been used. Glass beads may typically be characterized as generally comprising hollow, mostly spherical structures used as lightweight additives for cement compositions. When desired for use, glass beads may be used to reduce a cement composition weight while consequently increasing a composition's volume. Among other things, the glass beads should be suitable for use in wellbore applications, for example, in both onshore and offshore operations.
While glass bead additives have been developed heretofore, challenges exist with their successful use in applications where long term storage is desirable or for glass beads comprising a diverse size distribution. For example, in offshore applications, if no liquid additive of glass beads are available, the cement must be dry-blended with the glass beads onshore and then transferred to the offshore platform where the dry blend may be mixed with sea water and then pumped. Multiple dry cement blends may be required because each blend is typically formulated for a specific cementing depth because of differences in temperature, pore pressures, and formation fracture gradients through different geological zones. Thus, it is not uncommon for substantial quantities of individual dry cement blends to be discarded to make space for blends designed for the sequential and different sections of the well as they are being cemented. This operation may require multiple trips between the blending facility and the offshore platform and can be wasteful in terms of time and cost. Additionally, dry-blends of glass beads may not be physically stable when handled multiple times via pneumatic conveyance and can segregate based on density during transport and storage. As well as the fact that handling the dry-blends with glass beads multiple times may result in some level of damage to certain amount of the beads, thus reducing their effectiveness as a light weight additive.
However, even if using a liquid additive of glass beads, problems may still persist. For example, formulating a stable suspension of the glass beads for long-term storage may be difficult. This may be especially true for glass beads compositions comprising a diverse particle or multimodal particle size distribution. For these reasons, suspension agents may be used to suspend the beads; however, not all suspension agents are effective. For example, bentonite is not able to make a stable suspension using beads that are not uniform in size and specific gravity, as these formulations may comprise higher viscosities and may be unsuitable for suspension using aids with high viscosities and yield points.